Probably best known as the author of the words to "America the Beautiful," Bates was a prolific poet and a professor of English and head of the English department at Wellesley, where she had been a student in its earliest years.

Her father, a Congregational minister, died when Katharine was less than a month old. Her brothers had to go to work to help support the family, but Katharine was given an education. She received her B.A. from Wellesley College in 1880. She wrote to supplement her income. "Sleep" was published by The Atlantic Monthly during her undergraduate years at Wellesley.

A trip to Colorado in 1893 and the view from Pikes Peak inspired her poem, "America the Beautiful," published in The Congregationalist two years after she wrote it. The Boston Evening Transcript published a revised version in 1904, and the public adopted the idealistic poem quickly.

She helped found the New England Poetry Club in 1915 and served for a time as its president, and she was involved in a few social reform activities, working for labor reform and planning the College Settlements Association with Vida Scudder. She was raised in the Congregational faith of her ancestors; as an adult, she was deeply religious but could not find a church in whose faith she could be certain. She lived for twenty-five years with Katharine Coman, probably in what was termed a "romantic friendship." She wrote, after Coman died, "So much of me died with Katharine Coman that I`m sometimes not quite sure whether I`m alive or not."

Her teaching career was the central interest of her adult life, believing that through literature, human values could be revealed and developed.